[ubsan] Fall back to the fast unwinder when print_stacktrace=1

This makes it possible to get stacktrace info when print_stacktrace=1 on
Darwin (where the slow unwinder is not currently supported [1]). This
should not regress any other platforms.

[1] The thread about r300295 has a relatively recent discusion about
this. We should be able to enable the existing slow unwind functionality
for Darwin, but this needs more testing.

Differential Revision: https://reviews.llvm.org/D32517

llvm-svn: 301839

compiler-rt/lib/ubsan/ubsan_diag.cc

@@ -31,15 +31,16 @@ static void MaybePrintStackTrace(uptr pc, uptr bp) {
   // will definitely be called when we print the first diagnostics message.
   if (!flags()->print_stacktrace)
     return;
-  // We can only use slow unwind, as we don't have any information about stack
-  // top/bottom.
-  // FIXME: It's better to respect "fast_unwind_on_fatal" runtime flag and
-  // fetch stack top/bottom information if we have it (e.g. if we're running
-  // under ASan).
-  if (StackTrace::WillUseFastUnwind(false))
-    return;
+
+  uptr top = 0;
+  uptr bottom = 0;
+  bool request_fast_unwind = common_flags()->fast_unwind_on_fatal;
+  if (request_fast_unwind)
+    __sanitizer::GetThreadStackTopAndBottom(false, &top, &bottom);
+
   BufferedStackTrace stack;
-  stack.Unwind(kStackTraceMax, pc, bp, 0, 0, 0, false);
+  stack.Unwind(kStackTraceMax, pc, bp, nullptr, top, bottom,
+               request_fast_unwind);
   stack.Print();
 }
 

compiler-rt/test/ubsan/TestCases/Misc/missing_return.cpp

@@ -1,13 +1,10 @@
 // RUN: %clangxx -fsanitize=return -g %s -O3 -o %t
 // RUN: not %run %t 2>&1 | FileCheck %s
-// RUN: %env_ubsan_opts=print_stacktrace=1 not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-%os-STACKTRACE
+// RUN: %env_ubsan_opts=print_stacktrace=1 not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-STACKTRACE
 
 // CHECK: missing_return.cpp:[[@LINE+1]]:5: runtime error: execution reached the end of a value-returning function without returning a value
 int f() {
-// Slow stack unwinding is not available on Darwin for now, see
-// https://code.google.com/p/address-sanitizer/issues/detail?id=137
-// CHECK-Linux-STACKTRACE: #0 {{.*}}f(){{.*}}missing_return.cpp:[[@LINE-3]]
-// CHECK-FreeBSD-STACKTRACE: #0 {{.*}}f(void){{.*}}missing_return.cpp:[[@LINE-4]]
+// CHECK-STACKTRACE: #0 {{.*}}f{{.*}}missing_return.cpp:[[@LINE-1]]
 }
 
 int main(int, char **argv) {

compiler-rt/test/ubsan/TestCases/TypeCheck/misaligned.cpp

@@ -11,7 +11,7 @@
 // RUN: %run %t f1 2>&1 | FileCheck %s --check-prefix=CHECK-MEMFUN
 // RUN: %run %t n1 2>&1 | FileCheck %s --check-prefix=CHECK-NEW
 // RUN: %run %t u1 2>&1 | FileCheck %s --check-prefix=CHECK-UPCAST
-// RUN: %env_ubsan_opts=print_stacktrace=1 %run %t l1 2>&1 | FileCheck %s --check-prefix=CHECK-LOAD --check-prefix=CHECK-%os-STACK-LOAD
+// RUN: %env_ubsan_opts=print_stacktrace=1 %run %t l1 2>&1 | FileCheck %s --check-prefix=CHECK-LOAD --check-prefix=CHECK-STACK-LOAD
 
 // RUN: %clangxx -fsanitize=alignment -fno-sanitize-recover=alignment %s -O3 -o %t
 // RUN: not %run %t w1 2>&1 | FileCheck %s --check-prefix=CHECK-WILD
@@ -47,11 +47,7 @@ int main(int, char **argv) {
     // CHECK-LOAD-NEXT: {{^ 00 00 00 01 02 03 04  05}}
     // CHECK-LOAD-NEXT: {{^             \^}}
     return *p && 0;
-    // Slow stack unwinding is disabled on Darwin for now, see
-    // https://code.google.com/p/address-sanitizer/issues/detail?id=137
-    // CHECK-Linux-STACK-LOAD: #0 {{.*}}main{{.*}}misaligned.cpp
-    // Check for the already checked line to avoid lit error reports.
-    // CHECK-Darwin-STACK-LOAD: {{ }}
+    // CHECK-STACK-LOAD: #0 {{.*}}main{{.*}}misaligned.cpp
 
   case 's':
     // CHECK-STORE: misaligned.cpp:[[@LINE+4]]{{(:5)?}}: runtime error: store to misaligned address [[PTR:0x[0-9a-f]*]] for type 'int', which requires 4 byte alignment